Astaro Greymark was once a human ranger of the Argent Hounds, an order of monster hunters obsessed with lycanthropes and shapeshifters. He was sent to Last Lantern to investigate rumors of strange lunar magic in the Ashen Marches and search for a possible cure for lycanthropy. Astaro traveled with a wolf companion he had always treated as a brother rather than a pet, and over time he developed a deep admiration for the freedom, loyalty, and instinct he saw in wolves.

When the mages of Last Lantern created an experimental transformation using water from a Moonwell, Astaro volunteered to drink it. The transformation was agonizing, reshaping him into a Lupin, but he had felt an undeniable pull toward the wolf and believed the change was something he needed to understand. He still searches the Marches for answers about lycanthropy and transformation, all while wondering what the Argent Hounds will do when they discover that the ranger they sent to find a cure willingly became something they might consider a monster.